Where would Optimus Prime be without his archenemy, Megatron? Fortunately that's not a question we will need to answer just yet, because courtesy of the 2005 Heads on a Stick desk, we have an image of a prop used during the Transformers 3 filming in Chicago featuring the evil Decepticon leader's noggin! Like all the props we have been seeing, this is to assist the actors in acting and reacting to the robots who will be CGI'ed in later during post-production.
Maybe it is not much of a surprise that Megatron is returning for Transformers 3, since he was seen fleeing with Starscream at the end of Revenge of the Fallen. But this sighting confirms that Megatron will also be present in some form during the battle in Chicago alongside the other characters already seen on set in prop form or the form of stunt cars.